MikeFerrara:
Breath a tank dry sometime. You might be surprised at how little change in breathing effort you notice until the last breath or two.
On the other hand, you might be surprised at how much warning you do get
Depends on your regulator, your depth, tank size and your own personal sensitivity to things. On an AL80, for example, with a Conshelf in shallow water, even the most insensitive diver will get plenty (several minutes) of warning that air's getting low. With a Legend at 100', even the most sensitive diver will get no more than a 6 - 10 breath warning, and the "average" diver will probably only get three or four.
Either way, breathing a tank dry at depth (not the one on your back! You carry your "test tank" along as an extra piece of gear) is something that you may find beneficial.
** Before trying this drill at depth, you must be comfortable, have practiced in the shallow end of the swimming pool, and have a qualified buddy with whom you've practiced **
Use the type regulator and size tank you normally do. I always use a tank that's due for a VIP for this drill. Start at something around 300 psi so you'll get a few "normal" breaths before hitting IP in the tank. At the end of the exercise, switch back to your regular backgas and start a normal ascent. Do
not descend any deeper, or you may get water in your LP hose, the first stage, or even the tank. About half way to the surface, try clearing the reg on the "empty" tank and taking another breath from it. Repeat this when back on the boat or back ashore. You'll most likely be pleasantly surprized at the result.
VIP the tank before refilling it just to make sure you didn't get any water in it. If you did, overhaul your regulator too.
(By making sure I only get shallower after breathing a tank down like this, I've never had any problem with water in the reg or tank).
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The way the question's worded for the poll, my answer is yes. The way I think the question is intended, (running out of gas accidentally), the answer's no.
Rick
